package com.pc;

import com.sun.org.apache.bcel.internal.generic.NEW;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * @author by lvshh
 * @version 1.0
 * @date 2020/5/10 18:23
 */
public class ReadWriteLockDemo {

    /**
     * 自定义缓存
     */
    public static void main(String[] args) {
        myCache myCache = new myCache();
        for (int i = 1; i <= 5; i++) {
            final int temp = i;
            new Thread(()->{
                myCache.put(temp+"",temp + "");
            },String.valueOf(i)).start();
        }

        for (int i = 1; i <= 5; i++) {
            final int temp = i;
            new Thread(()->{
                myCache.get(temp+"");
            },String.valueOf(i)).start();
        }

    }
}
class myCache{
    private volatile Map<String,Object>  map = new HashMap<>();
    //读写锁：更加细粒度的控制
    private ReadWriteLock lock = new ReentrantReadWriteLock();

    //存，写，写入的时候只希望同时只有一个线程再写，
    public void put(String key,Object value){
        lock.writeLock().lock();

        try {
            System.out.println(Thread.currentThread().getName() + "写入" + key);
            map.put(key,value);
            System.out.println(Thread.currentThread().getName() + "写入OK");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.writeLock().unlock();
        }

    }

    //取，读，所有人都可以读
    public void get(String key){
        lock.readLock().lock();

        try {
            System.out.println(Thread.currentThread().getName() + "读取" + key);
            Object o = map.get(key);
            System.out.println(Thread.currentThread().getName() + "读取OK" );
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.readLock().unlock();
        }

    }
}
